What stops the NRF_LOG_ UART logging output?

[Hugo Habicht]

Hi All,

the logging output (NRF_LOG_...) in the SDK17 via the UART works fine on the DK board (only change from the HRS example was the NRF_LOG_BACKEND_UART_TX_PIN has been changed to p0.19).

But on our board there is no output on that pin. UART seems to be initialised correctly and also PSEL.TXD ist set to 0x13 (19) correctly. When I stop the system with the debugger it is hanging in serial_tx(). m_xfer_done stays false. Unfortunately the hardware designers do not allow reading of the TXD register, so I have no indication if at least one character has been written.

What hardware pin / setting can affect the output? Is there some handshake mechanism that we missed?

Regards,

[Hugo Habicht]

Hi All,

we figured it out. The DK is running with a Vdd of 3V and our own board with an external battery and DC-DC giving a Vdd of 1.8V. The serial to USB converter of course does not read those signals so we'll put in a level shifter.

I wanted to delete the post above but maybe it helps somebody stumbling into the same trap.

Regards,